Speech signals within a motor vehicle are typically recorded with a single microphone or microphone array in a fixed position within the car. If the microphone is placed as close as possible to the talker, the signal-to-noise ratio is increased, but the signal varies in loudness and timbre as the talker moves. If the microphone is placed farther away from the talker, loudness and timbre variations are reduced, but the background noise is harder to strip away from the speech signal.